Carotid artery disease: the influence of diabetes mellitus.

Patients with diabetes mellitus are more prone to stroke than non-diabetic patients. Using Duplex ultrasound imaging of the carotid bifurcation, we have found it possible to classify atherosclerotic plaques into four groups which appear to reflect the plaque pathology. Using this classification we have found that diabetics and non-diabetics have similar ultrasound plaque type distributions in symptomatic patients. Further subdivision of the diabetic patients on the basis of their mode of diabetic control has shown that insulin treated diabetics tend to show little evidence of intraplaque haemorrhage and ulceration. These features suggest that factors other than atherosclerosis at the carotid bifurcation may be responsible for the increased stroke risk in diabetic patients. Diabetic microangiopathy and reduced vessel compliance due to medial calcification have been suggested as possible factors. Insulin treatment of diabetics may protect against the development of occlusive atherosclerosis.